Machine for and method of applying varnish to sheets of fibrous material



Apriii i2 9 19270 L. T. FREDERECK- MACHINE FOR AND METHOD OF APPLYINGVARNISH T0 SHEET-S OF FIBROUS MATERIAL Filed March 2', 1925 mm-shm 1lamb A ril 12 1927.

p L. 'r. FREDERICK MACHINE FOR AND METHOD OF APPLYING VARNISH T0 SHEETS0F F'IBROUS MATERIAL Filed March 2. 1925 2 Sheets-Sheet 2 jam Iozzzb ffrfiderz'ck 624m o Jj Patented Apr. 12, 1927.

UNITED STATES P 1,624,094 ATENT OFFICE.

I LOUIS T. FREDERICK. OF VALPARAISO, INDIANA, ASSIGNOR TO FIBROCINSULATION COMPANY, OF VALPARAISO, INDIANA, A CORPORATION OF INDIANA.

MACHINE FOR AND METHOD OF APPLYING VARNISH T0 SHEETS OF FIBROUSMATERIAL.

Application filed March 2, 1925. Serial No. 12,497.

It is well known that a composite material usable for silent gears.insulation and many other purposes is made by first impregnating sheetsof paper or other fibrous material with a binder, then laying a pluralitof the impregnated sheets one upon anot ier and finally consolidatingthe whole by means of pressure usually accompanied by the action ofheat. One of the well known binders employed is a synthetic resin orcondensation product formed from phenol and formaldehyde and known asbakelite, this being a substance which hardens under heat and pressure.

It is common in impregnating the fibrous material to pass a strip of itthrough a bath of the liquid resin or varnish dissolved in alcohol orother solvent. These strips are many inches and sometimes several feetwide, and considerable difliculty has been found in distributing thebinder uniformly across the width of the strip. It is found that whenthe strip is assed through a bath and then over a distributing rollerthe tendency is for the roller to remove more of the varnish from theends than from the mid portion. The result is that the finished productis non-uniform and unsatisfactory. To remedy this manufacturers haveresorted to the expedient of thinning the varnish by increasing theamount of solvent. By thus thinning the varnish it readily flows fromthe strip and the amount left on it is more uniform but this method hasdisadvantages because it is affected bv temperature, by the speed of thestrip and by the amount of solvent contained in the varnish. Furthermorethis method is expensive because the solvent is expensive and much of itis wasted by evaporating and assin off into the air. The object of myinvention is to avoid these difficulties and to obtain a uniformdistribution across the sheet without increasing the amount of solventin the varnish. Generally speaking I attain this object by stretchingthe strip toward the mid portion, that is, by requiring the mid portionto pass over a stripper or wiper which is bowed at the mid portion, thusexerting greater pressure on the strip at the mid portion andconsequently forcing from the mid portion the same amount as is forcedfrom the marginal portions of the strip.

I accomplish my object in the manner and Figure 4 is a sectional detailon the line I 44 Figure 3.

Figure 5 is a vertical section through the bath on the line 55 Figure 3.

Figure dis a vertical section of the bath equipped with somewhatmodified stripping and guiding means.

Figure 7 is a vertical section on the line 77 Figure 6.

Like numerals denote like parts throughout the several views.

Referring first to the form shown in Figures 1 to 5 inclusive, the dryerhas a housing 1 which is heated in any suitable manner,

for example, by means of steam pipes 2.

The impregnated strip passes in through a port 4 shown at the right endof Figures 1 and 2, and emerges through a port 6 shown at the left endof Figures 1 and 2. Any suitable means may be provided for drawing thestrip 8 through the machine. In the present case there is a roller 10over which the strip passes'and a traction roller 12 located adjacent toit for pulling the strip through. The roller 10 is rotated by means of aworm gear 14 engaged by a worm 16 driven by cone pulleys 18 or othersuitable source of ower.

greatly varied.

Referring now to the part of the mechanism which is more closelyconcerned with From the rollers 10 and 12 the strip passeson to astoragereel 19' guide plates 48 are associated with the second dipping rollerto supportit and guide the strip through the machine. From the dippingroller 46 the strip rises to the stripping elements which servev toremove the surplus hinder from the fabric and which are of the essenceof the invention.

In the design shown in Figures 3, 4 and the first stripping element 49is in the form of a bar or rod which is arranged horizontally above thelevel of the liquid and is of a length somewhat greater than the widthof the fabric. It is supported at the ends in a swinging frame whichincludes side plates 50 and a rigid cross bar 52. This frame ispivotally supported on the side guides 48 by means of bolts 54 and theconstruction is such that the weight of the frame and stripping elementcauses the latter to press against the fabric and strip the excessliquid from it. The stripping element is bowed at the center by means ofa set screw 56 which screws in the cross bar 52 and at its inner endengages the mid portion of the stripping element. By rotating this screwinward towards the stripping element it may be caused to bow the latterto any desired degree of curvature.

From the first stripping element the fabric strip passes preferably to asecond strip ping element 56 which is bowed upward against the strip soas to increase the pressure at the mid portion thereof as does thestripper 49. This element 56 is mounted in the side guides 48 and thedegree of curvature is regulated by a set screw 58 mounted in a bracket60.

In operation, when the mechanism shown at the left end of Figure 1 isfunctioning and drawing the strip through the machine the fabric passesfrom the supply roll 34 over the guide roll 40, thence beneath thedipping rolls 44, 46 and thence up to the stripping elements 49, 56. Iam not positive as to the exact actionof the stripping elements, thatis, whether they actually exert greater pressure at the mid portion ofthe strip or whether there is a natural tendency for the strip to bulgeat-the mid portion and the stripper compensates for this and exertsuniform pressure. On the other hand it may be that capillary actiontends to hold the liquid more tenaciously at the mid portion than at themarginal portion, but in any event I have found that the bowing of thestripper makes it possible to equalize the amount of varnish retained onthe strip, and by changing the curvature of the stripper thedistribution may be regulated and the amount of varnish remaining at thecenter may be increased or decreased at will.

As the strip leaves the final stripping element 56 it passes into thehousing of the dryer where it becomes dry and from which it passes ontothe receiving roll 19. It is then ready to be cut into sheets andconsolidated in a bot press.

The strippers shown in Figures 3, 4 and 5 are non-rotary. Hence anappreciable amount of friction is generated. In some cases where a weakpaper is to be impregnated it is desirable to reduce the amount offriction, and I accomplish this by the mechanism shown in Figure 6 inwhich all of the parts are the same as before except that instead ofusing the second fixed stripper or wiper 56 I substitute a stripper 62.This is in the form of a roller which bulges toward the center as bestshown in Figure 7 This roller is rotatably supported upon gudgeons 64journaled in side plates 66 which are analogous to the side plates 48but have slots 68 in which the gudgeons may be seated. These slots areshown in dotted lines in the .upper left portion of Figure 6. Thismechanism has the same general effect as before, the disadvantage fromthe structural standpoint, however, being that a somewhat heavierstripper element is necessary and it is not ad]ustable exce t in thesense that other rollers having di erent degrees of curvature ma besubstituted.

It will be observe that the mechanism by which the varnish may bedistributed is quite simple, being not very different from the ordinaryguide rollers which have been commonly employed in dipping baths. ICurvature, however, has made it possible to gain a uniformityofdistribution of the varnish, and this is of vital importance inproducing a uniform product from the impregnated material. I

It will be understood, of course, that the number of bowed or curvedstrippers may be varied but I have found that two is usually the bestnumber.

While I have shown non-rotary curved or bulged strippers in Figures 1 to5 inclusive and a rotary curvedor bulged stripper in Figures 6 and 7, Ido not herein claim the rotary one but do so in a companion applicationfiled on the 2nd day of March, 1925, Serial No. 12,499.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is: p

1. The method of distributing liquid uniformly upon a fibrous sheetconsisting in first applying an excessive amount of liquid to the sheetand then removing the surplus by manner,

subjecting the-*sheet to a stripping action in which theKcentra'Iportion of the sheet is stretched to a greater extent than the marginalportionsthereof.

'2. The' met-hod of applying a binder to a fabric' i-n the form of aliquid consisting in first applying to the strip an excess of the binderin liquid form, then removing the excess by exerting in a'straight lineacross the strip from edge to edge and with a motion lengthwise of thestrip, a pressure such as to cause the strip to bulge at the centralportion.

3. The method of impregnating a strip of fibrous material consisting infirst applying an excess of the liquid to the strip and then removingthe excess by causing the strip to travel over a stationary elementhaving a curvature such that the mid portion of the strip is required totravel a longer path thanthe marginal portions.

4:. The method of impregnating a strip of fibrous material wlth a binderconsisting in passing the strip through a bath of the binder in liquidform, then pressing upon the strip in such manner as to cause agraduated bulge at the mid portion for uniform removal of the excessliquid, and then drying the strip.

5. In a machine for applying varnish to a fabric, means for applying anexcessive amount of the varnish, and a curved stri per over which theWetted strip passes, t e stripper being curved to cause the strip inpassing to bulge at the center.

6. In a machine for applying varnish to a fabric, a bath for containingtheliquid varnish, means for guiding a strip of the fabric through thebath, and a curved stripper over which the wetted strip passes after ithas emerged from the liquid, the stripper being curved to cause thestrip in passing to bulge at the center, and thus have the surplusvarnish removed uniformly across the stri 7. Apparatus for impregnatinga fa ric with varnish, the apparatus having a bath for applying'anexcess quantity of the'varnish, a curved stripper-which bulges at thecenter, and means ifor causing a strip of the fabric to pass firstthrough the bath and then over the stripper.

8. Apparatus for impregnating a fabricwith varnish, the apparatus havingabath for applying an excess quantity otthe varnish, a curved stripperwhich bulges at the center, means for causing a strip of the fabric topass first through the bath and then over the stripper, and means fordrying the strip as itleaves the stripper.

9. In a machine for applying varnish to a fabric, a bath for containingthe liquid varnish, means for guiding a strip of the fabric through thebath, and a stripper for removing the surplus liquid from the stripafter it leaves the bath, said stripper being arranged crosswise ofthe.strip and being curved outward toward the strip at the mid portion,and means for yieldingly pressing said stripper a ainst the strip;

10. In a mac ine for applying varnish to a fabric, a bath for containingthe liquid varnish, means for guiding a strip of the fabric through thebath, and a curved stripper over which the wetted stri passes after ithas emerged from the liquid the stripper being curved to cause the stripin passing to bulge at the center, and being non-rotary for makingsliding contact with the strip.

11. In a machine for applying varnish. to a fabric, a bath forcontaining the liquid varnish, means for guiding a strip of the fabricthrough the bath, and a stripperfor removing the surplus liquid from thestrip after it leaves the bath, said stripper being arranged crosswiseof the strip and being curved outward toward the strip at the midportion, and means for yieldingly pressing said stripper against thestrip, the stripper being non-rotary for making frictional contact withthe strip as it passes.

In witness whereof, I have hereunto subscribed my name,

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